Transcutaneous Flow Measurements in In-Situ Bypasses: An Assessment of Duplex Scanning

Abstract

Measurement of laminar flow using an ultrasound scanner was shown to have a high degree of correlation with quantified timed flows (r = 0.98, p ≤ .001). Sixty-one in-situ bypasses had flow assessed both proximally and dis tally. Mean fistula flow (proximal-distal flows) for time periods 1-8 weeks, 3 to 8, and 9+ months were 108, 85, and 16mls respectively. Distal bypass flow remained constant despite a significant decrease in fistula flow between the later time periods (p ≤ .001) (unpaired t-test). There was no evidence from the study that proximal flow through fistulas of varying resistances adversely affected the distal bypass flow.